Hodgkin and Reed-Sternberg (HRS) cells, the neoplastic cells of Hodgkin's disease (HD), represent only a minority of the cellular infiltrate in affected tissue. Therefore, rearrangements of the immunoglobulin heavy-chain (IgH) gene detected in DNA extracted from an entire Hodgkin's lymph node cannot be attributed to the HRS cells and cannot be used as an argument for the B-cell origin of HRS cells. We developed a new method for the amplification of rearranged DNA of the IgH gene from single cells. Using 6 "forward primers" which were constructed corresponding to consensus sequences of the 6 known families of the IgH variable (V) region (framework region I) and a mix of 2 "reverse primers" corresponding to consensus sequences of the different joining (J) segments, rearrangements of all 6 V-families were detected in human peripheral blood lymphocytes. Rearranged IgH DNA could be amplified from single cells of B-cell lymphoma-cell lines and from 13 patients with B-cell non-Hodgkin's lymphomas. However, analysis of HRS cells isolated from lymph nodes of 13 patients with Hodgkin's disease did not show any rearrangement of the IgH gene locus. These findings, obtained by polymerase chain reaction (PCR) on isolated single HRS cells, contrast with previous studies that used Southern-blot analysis of entire tissues affected by Hodgkin's disease. We conclude that the neoplastic HRS cells in Hodgkin's disease--with the possible exception of the nodular paragranuloma subtype--are probably not derived from B cells.